Exam: Work, Power, and Machines
Give two examples of kinetic energy becoming potential energy.



Give two examples of potential energy becoming kinetic energy.


What is the formula for calculating the efficiency of a machine?

Why do you always multiply the efficiency by 100?

If a container weighs 58 N, then it should take 580 J of work to move it 10 m up a ramp.  However, it actually takes 640 J of energy to move it due to friction.  What is the efficiency of this system?

Define and give an example in parenthesis:
open system

closed system

What is a perpetual motion machine?

Why is it impossible to build a perpetual motion machine?

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